/*
 * Copyright (c) 2007-2013, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */
package com.sun.org.apache.bcel.internal.generic;

/* ====================================================================
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 2001 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Apache" and "Apache Software Foundation" and
 *    "Apache BCEL" must not be used to endorse or promote products
 *    derived from this software without prior written permission. For
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 * 5. Products derived from this software may not be called "Apache",
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 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
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 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 */

import com.sun.org.apache.bcel.internal.Constants;
import com.sun.org.apache.bcel.internal.classfile.*;
import java.util.Objects;

/**
 * This class represents a local variable within a method. It contains its
 * scope, name and type. The generated LocalVariable object can be obtained
 * with getLocalVariable which needs the instruction list and the constant
 * pool as parameters.
 *
 * @author  <A HREF="mailto:markus.dahm@berlin.de">M. Dahm</A>
 * @see     LocalVariable
 * @see     MethodGen
 */
public class LocalVariableGen implements InstructionTargeter, NamedAndTyped, Cloneable, java.io.Serializable {
    private final int index;
    private String name;
    private Type type;
    private InstructionHandle start, end;

    /**
     * Generate a local variable that with index `index'. Note that double and long
     * variables need two indexs. Index indices have to be provided by the user.
     *
     * @param index index of local variable
     * @param name its name
     * @param type its type
     * @param start from where the instruction is valid (null means from the start)
     * @param end until where the instruction is valid (null means to the end)
     */
    public LocalVariableGen(int index, String name, Type type, InstructionHandle start, InstructionHandle end) {
        if ((index < 0) || (index > Constants.MAX_SHORT))
            throw new ClassGenException("Invalid index index: " + index);

        this.name = name;
        this.type = type;
        this.index = index;
        setStart(start);
        setEnd(end);
    }

    /**
     * Get LocalVariable object.
     *
     * This relies on that the instruction list has already been dumped to byte code or
     * or that the `setPositions' methods has been called for the instruction list.
     *
     * Note that for local variables whose scope end at the last
     * instruction of the method's code, the JVM specification is ambiguous:
     * both a start_pc+length ending at the last instruction and
     * start_pc+length ending at first index beyond the end of the code are
     * valid.
     *
     * @param il instruction list (byte code) which this variable belongs to
     * @param cp constant pool
     */
    public LocalVariable getLocalVariable(ConstantPoolGen cp) {
        int start_pc = start.getPosition();
        int length = end.getPosition() - start_pc;

        if (length > 0)
            length += end.getInstruction().getLength();

        int name_index = cp.addUtf8(name);
        int signature_index = cp.addUtf8(type.getSignature());

        return new LocalVariable(start_pc, length, name_index, signature_index, index, cp.getConstantPool());
    }

    public int getIndex() {
        return index;
    }

    @Override
    public void setName(String name) {
        this.name = name;
    }

    @Override
    public String getName() {
        return name;
    }

    @Override
    public void setType(Type type) {
        this.type = type;
    }

    @Override
    public Type getType() {
        return type;
    }

    public InstructionHandle getStart() {
        return start;
    }

    public InstructionHandle getEnd() {
        return end;
    }

    /**
     * Remove this from any known HashSet in which it might be registered.
     */
    void notifyTargetChanging() {
        // hashCode depends on 'index', 'start', and 'end'.
        // Therefore before changing any of these values we
        // need to unregister 'this' from any HashSet where
        // this is registered, and then we need to add it
        // back...

        // Unregister 'this' from the HashSet held by 'start'.
        BranchInstruction.notifyTargetChanging(this.start, this);
        if (this.end != this.start) {
            // Since hashCode() is going to change we need to unregister
            // 'this' both form 'start' and 'end'.
            // Unregister 'this' from the HashSet held by 'end'.
            BranchInstruction.notifyTargetChanging(this.end, this);
        }
    }

    /**
     * Add back 'this' in all HashSet in which it should be registered.
     **/
    void notifyTargetChanged() {
        // hashCode depends on 'index', 'start', and 'end'.
        // Therefore before changing any of these values we
        // need to unregister 'this' from any HashSet where
        // this is registered, and then we need to add it
        // back...

        // Register 'this' in the HashSet held by start.
        BranchInstruction.notifyTargetChanged(this.start, this);
        if (this.end != this.start) {
            // Since hashCode() has changed we need to register
            // 'this' again in 'end'.
            // Add back 'this' in the HashSet held by 'end'.
            BranchInstruction.notifyTargetChanged(this.end, this);
        }
    }

    public final void setStart(InstructionHandle start) {

        // Call notifyTargetChanging *before* modifying this,
        // as the code triggered by notifyTargetChanging
        // depends on this pointing to the 'old' start.
        notifyTargetChanging();

        this.start = start;

        // call notifyTargetChanged *after* modifying this,
        // as the code triggered by notifyTargetChanged
        // depends on this pointing to the 'new' start.
        notifyTargetChanged();
    }

    public final void setEnd(InstructionHandle end) {
        // call notifyTargetChanging *before* modifying this,
        // as the code triggered by notifyTargetChanging
        // depends on this pointing to the 'old' end.
        // Unregister 'this' from the HashSet held by the 'old' end.
        notifyTargetChanging();

        this.end = end;

        // call notifyTargetChanged *after* modifying this,
        // as the code triggered by notifyTargetChanged
        // depends on this pointing to the 'new' end.
        // Register 'this' in the HashSet held by the 'new' end.
        notifyTargetChanged();

    }

    /**
     * @param old_ih old target, either start or end
     * @param new_ih new target
     */
    @Override
    public void updateTarget(InstructionHandle old_ih, InstructionHandle new_ih) {
        boolean targeted = false;

        if (start == old_ih) {
            targeted = true;
            setStart(new_ih);
        }

        if (end == old_ih) {
            targeted = true;
            setEnd(new_ih);
        }

        if (!targeted)
            throw new ClassGenException("Not targeting " + old_ih + ", but {" + start + ", " + end + "}");
    }

    /**
     * @return true, if ih is target of this variable
     */
    @Override
    public boolean containsTarget(InstructionHandle ih) {
        return (start == ih) || (end == ih);
    }

    /**
     * We consider two local variables to be equal, if they use the same index and
     * are valid in the same range.
     */
    @Override
    public boolean equals(Object o) {
        if (o == this)
            return true;

        if (!(o instanceof LocalVariableGen))
            return false;

        LocalVariableGen l = (LocalVariableGen) o;
        return (l.index == index) && (l.start == start) && (l.end == end);
    }

    @Override
    public int hashCode() {
        int hash = 7;
        hash = 59 * hash + this.index;
        hash = 59 * hash + Objects.hashCode(this.start);
        hash = 59 * hash + Objects.hashCode(this.end);
        return hash;
    }

    @Override
    public String toString() {
        return "LocalVariableGen(" + name + ", " + type + ", " + start + ", " + end + ")";
    }

    @Override
    public Object clone() {
        try {
            return super.clone();
        } catch (CloneNotSupportedException e) {
            System.err.println(e);
            return null;
        }
    }
}
